1. Technical Field
This invention relates to antenna systems and more particularly to techniques for laminating a dielectric substrate to an antenna housing.
2. Discussion
Conventional antenna designs, such as those utilized in missiles, are frequently large and bulky structures that are mounted inside of the missile. Aside from being bulky, these antennas have to be designed to radiate through an air space as well as through the wall of a missile. The result is that such antenna systems are often inefficient.
Antenna assemblies which will save space in missiles and which have simpler and less costly fabrication requirements have been described to some extent by the following United States patents, the disclosures of which are incorporated herein by reference: U.S. Pat. No. 3,798,652, issued to Willilams; U.S. Pat. No. 4,010,470, issued to Jones; U.S. Pat. No. 4,431,996, issued to Milligan; U.S. Pat. No. 4,494,121, issued to Walter et al; and U.S. Pat. No. 4,516,131, issued to Bayha. The above-cited references are exemplary in the art and disclose antenna systems employed in missiles, projectiles, and radomes of aircraft. Even in these examples, the fabrication of antenna assemblies used in missile systems typically are comparatively costly because of processes which include etching, machining and a number of plating operations.
To solve these problems, there has been developed a design of an antenna assembly which has simplified fabrication requirements and which occupies a reduced amount of space. This invention is described in the above-referenced, copending applilcation entitled, "TDD Antenna--Foil Formed, Substrate Loaded Laser Welded Assembly". That application discloses an antenna which is formed by building a shell housing using a punch press operation. This housing can be made of various materials including aluminum or stainless steel. A dielectric with a load and a connector fits into the housing. Then, a back is placed onto the assembly and the unit is enclosed by laser welding.
The above design allows the fabrication of the housing to be constructed with the antenna features built-in, and is simpler and less costly than prior designs. However, it has been found that intimate contact between the dielectric and the housing could not be consistently maintained. This results in an air gap between the dielectric and the aperture housing. This air gap introduces changes into the radio frequency (RF) pattern. The result is distortion of the RF signal.
Changes in temperature make the separation problem worse. When the antenna assemblies are installed into the interior of a missile they are wrapped in an epoxy material which must be cured at high temperatures. For example, this curing temperature may be above 375.degree. F. Subjecting the antenna assembly to these temperatures has resulted in separation of the dielectric from the housing. Conventional methods such as using a bonding material to attach the dielectric to the housing are not generally feasible. This is because the bonding material itself would create an unacceptable gap between the dielectric and the housing.
Thus, it would be desirable to have a method of attaching the dielectric to the antenna housing which would maintain intimate contact between the two materials throughout a wide temperature range, such as between 600.degree. F. and -65.degree. F. The present invention is intended to satisfy this need.